Transforming Robot Production Pipeline Volume 10: Compositing

In this lesson we'll look at how we can finish off our particles by adding in a little bit more dust noise, as well as how we can render out a rock pass, to better integrate our particles. Now if you open up 21_begin, I've actually done a little bit of work on this in between the lessons. So let's quickly go through what work was done. Very similar to the last lesson, we set up this exact same Roto workflow on our other set of particles. So you can see here, on the right dust, we have these Roto shapes controlling our particles and making sure they layer correctly with our image or with the foreground image. Now beyond that, I've merged these two together before processing them further. And this is almost just an organization thing. Having a few merges out here is much easier than having quite a few merges in my main tree trunk. So in this case, we've merged are particles together-- the hit particles. And we've done actually a little bit more processing on these. So to break up the shape and have a wispier, softer cloud look, we actually came in and multiplied these particles by another noise pattern. So if we take a look here, we're bringing in our alpha channel from our main foreground. So if we see this, and then we're shuffling the alpha into all the channels, inverting it so we have an inverted alpha, and then we plug this into a noise mask. So we have noise everywhere, except for inside of the alpha channel. From there, we can do a little blur, and then multiply it on top of our original particles. And what this does is it adds yet another layer of complexity. After that, we clamp this again, to remove our alpha channels below zero. And then composite this in normally. Now with particles, you're going to have to keep on layering these levels of detail. It usually takes quite a few passes of noise, animated noise, and so forth to make these particles look more realistic. And because we're working with such a complex, real-world phenomena, we have to add together quite a lot of noise to have that random movement that particles have. Now we've also gone in and done a little bit of color correcting and done some Roto on our front car particles. So we can see the change here. Here, the primary changes is we pulled back this blur/dilate combination. It was a little bit too strong for these particles very close to the screen. So we pulled that back quite a bit. And we added yet another Roto shape to remove some of these particles that were moving far too fast and to soften up the edges of these particles as they float away from our car. So with all this done, we now have a much more solid particle integration with our scene. We'll notice the slide particles look much more dynamic and have much more motion, now that we're bringing together and multiplying together multiple noise paths. So in the end, we have this nice composite. And these particles need to be subtle to really sell them correctly. They're not going to be covering up the entire composite. So we want them to live in the background, but still exist as a visual element to help tie together all of our various pieces. Now one thing that I noticed was missing is pieces of gravel and rocks jumping up from our car tires as we're driving along. So I took one of our particle scenes and just change it up a little bit to emit those rocks. So we can see here, we've brought in a blocks.fbx, which is an FBX from our Architectural Destruction in Maya course. And we've just read this into the six particle slots of a particle emitter. And then just as we have before, we've animated this on and off in certain areas to emit rocks from our car. Now for this, we've actually plugged in quite a few different textures. We start with a normal constant, generate three different noise patterns at different sizes, and then color correct them to different levels of brightness and browned saturation. So this is creating a lot of different objects that look like different-colored rocks. From there, we have our Particle Emitter set on input, in order, random. And it will come in, grab a particle, grab its texture, and then render out this rock being flung from our car. Now this again, has a pretty high sampling. So we have a lot of motion blur on this. And once we bring this in, it's just going to be a simple over on top of our dust cloud particles. So if I jump back to our 21_begin composite. I'm just going to import the rocks render from that Nuke script. We can see those here. And they will be generated or created, I believe, in a few of these frames. So if we look at our alpha channel, we can see these rocks being generated. And they're a little bit small. But let's now merge these into our particle stream before we actually add in this extra noise here. So let's just grab this, merge multiply, grab another A2 pipe, and plug this in. Actually, before this, let's plug this into our merge over of all our particles. So now we have these rocks flying from our car and appearing in our final composite. So that just adds in one, little final level of detail to our particles that help the integration of this being a moving and living scene, with a dynamic car driving, kicking up particles, and then our foreground object also kicking up particles. Now you'll notice there's still quite a bit of work left to do on these particles. However, I do know that we are going to do a pretty heavy camera shake, as well as add some motion blur to the background. If you'll notice, we shot this again, very, very low-motion blur, very high shutter, knowing that we were going to do a 3D camera solve and then reintroduce the motion blur here, in Nuke. So these particles are essentially at a point where I like to say, all right, let's see what they look like after they're blurred and after we have some more compositing done to these pieces. So with our particles at a good stopping point, let's take a look in the next lesson at how we can shoot and analyze plate for lens distortion. And then apply that to our foreground footage, to have correct camera bowing and curvature, based on whichever camera we shot this with. So to recap this lesson, we took a look at how we can add on additional noise, using the alpha channel from our foreground, to make our particles look more realistic; how we could change the color correction and the blending of our particles; again, to increase the realism; and how we can layer in more particle effects, like rocks and gravel to again, add some of that detail, add a little bit of movement in areas where there should be. So with our particles done, let's now take a look at lens distortion.